Current ideas and research in psychology, neuroscience, and neurology

motor

Parkinson’s disease is what is known as a slowly progressing neurological disorder. It usually has an onset around or after age 60 with an average of 14 years between diagnosis and death (which means that there is a slightly reduced lifespan compared to peers without Parkinson’s disease). While symptoms vary – resting tremor, gait disturbances, flattened emotions – there are some early signs that indicate that someone might have or be developing Parkinson’s disease. If you or someone you know is experiencing a number of these symptoms, contact your primary care physician. Having one or all of these symptoms does not mean you have Parkinson’s disease (I know individuals with a number of these symptoms but they do not have Parkinson’s disease) but if you are experiencing some of them and are concerned, talk with your doctor.

Shaking when at rest. This usually occurs on one side of the body, often in your extremities, such as a finger or foot or a hand. The shaking might also be worse when you are tired or stressed.

Balance problems – you feel like you are more unsteady on your feet; you might not have fallen but you feel like you might.

Lightheadedness when arising from a sitting position. This is called orthostatic hypotension (drop in blood pressure that occurs when changing from a non-moving state). Again, this is only one of many potential signs; by itself it is not concerning.

Changes in your handwriting, particularly if it seems sloppier, smaller, or slower.

Changes in your fine finger dexterity – difficulty with small buttons, for example.

Stiffness in joints or pain in parts of your body. This can seem like arthritis (and might coexist with arthritis) but is a symptom of Parkinson’s disease.

Have people telling you that you do not seem as engaged in life as you used to be (i.e., emotionally). This is one way I’ve heard people talk about how the “masked face” of Parkinson’s appears. A person might appear less emotional than he used to (or even more sad).

Feeling like your thinking has slowed down.

Feelings of depression or just that you do not have the energy or desire to do as much as you used to do. What is often mistaken as depression is apathy, which is quite common in Parkinson’s disease. Apathy can be a sign of depression but someone can be apathetic without being depressed.

There are other signs of Parkinson’s disease but this list covers the major and some of the minor ones. Which ones are major? Loss (reduction) of sense of smell, constipation, and resting tremor are all very common in Parkinson’s disease; loss of smell and constipation often occur before tremor so they are often missed as signs of potential Parkinson’s disease. Having none, one, or all of the above symptoms does not mean you do or do not have Parkinson’s disease. Many of the symptoms above can be signs of other disorders or can be part of the ‘normal’ aging process (e.g., slightly stooped posture, slowed thinking). However, if you are experiencing some of these symptoms, please talk to your doctor, even if for nothing more than ease of mind.

The corticospinal tract is a descending motor pathway originating in the Primary Motor Cortex (Brodmann’s area 4) and terminating at various levels in the ventral horn of the spinal cord. The corticospinal tract descends through the posterior limb of the internal capsule then down through the cerebral peduncles into the brainstem. In the brainstem the corticospinal tract remains in the ventral portion, passing through the pyramids on its way down. In the caudal brainstem (just above where the spinal cord starts) 90% of the the corticospinal tract decussates (crosses) to the contralateral (opposite) side and continues down through the dorsolateral spinal cord. This portion controls limb movements. The remaining 10% remains in the ventral spinal cord and is largely responsible for bilateral axial (trunk) movement. From the dorsolateral spinal cord, the axon (that started in the cortex) enters the ventral horn of the spinal cord at the appropriate level (e.g., cervical for arms or lumbar for legs) then exits through the ventral root to terminate on the appropriate muscles.

Through this tract, the cortex controls much of the movement of the body; as such, it’s vitally important for our functioning. Damage to the tract results in an upper motor neuron disorder, with paresis (weakness instead of complete paralysis) and the Babinski reflex fairly common symptoms. Soon after damage, a patient might have flaccid paralysis though with little to no movement of the affected limb(s). As the body starts to recover slightly, spastic paralysis usually sets in with jerky, often uncontrolled limb movements. The corticospinal tract is one of the largest pathways in the central nervous system; it’s one of the most important for motor functioning as well.